Make a combustion gun out of a seltzer bottle? I'd drill out the bottom, and epoxy in 1/2" pipe. Unscrew the cap to fill. I have a small piezo ignightor from the pill botle gun I had explode on me, so I'll use that. I was thinking of stuffin the seltzer bottle inside 4" ABS, because I have it. Just in case it ever explodes. Will it work? Can it stand a combustion?

why would you have a 1/2" barrel with a 4" chamber? first of all the gun would look stupid, and second if you had a 4" chamber you would want to go with 2" or 1 1/2" barrel. i belive hes going with the ghetto approuch and making this out of stuff he has. and yes it will work fine as long as you get the fuel to air mix right. if the bottle does explode its not brittle like a pill bottle, so there shouldn't be any shrapnel. you should be fine without the pipe but if you have it lying around go for it.